STATE COLLEGE, Pa. (AP) -- Penn State's defense needs work after watching Central Florida roll up 507 yards in a 34-31 loss on Saturday night. The offense, however, might be just fine.

Freshman quarterback Christian Hackenberg completed 21 of 28 passes, Allen Robinson hauled in nine receptions for 143 yards and running back Zack Zwinak reasserted himself as the clear starter with three touchdowns.

Penn State's 455 yards of total offense wasn't enough to counteract UCF. One thing that would have helped, some offensive players said, was a faster start.

''I would say the biggest takeaway is that we need to start fast,'' Robinson said. ''We are in the Big Ten playing against some great offenses and people are going to put points up early, so we need to get going early and start off fast.''

The Nittany Lions fell behind 21-10 at the half and 31-17 after three quarters. They outscored the Knights 14-3 in the fourth quarter, but the comeback fell short.

Despite the two-touchdown deficit, many Lions said they never thought they were incapable of rallying.

Penn St running back Zach Zwinak (28) recovers his own fumble during the fourth quarter of an NCAA c …

''Coach (O'Brien) preached to us - it's one play at a time, one drive at a time. I think that we never really counted ourselves out of the game,'' Robinson said.

''It was a similar situation last year against Northwestern. I think that it's something all of our guys really thought about. We put some plays together, put a few drives together and we just came up a little short.''

Even the defense, which was gashed for 10 plays of 20 yards or longer, thought it could tighten up enough to help craft a comeback.

''Even when we were down, we still believed we had a chance to win the game,'' defensive tackle DaQuan Jones said. ''It's Penn State, you're going to get a tough nitty-gritty team. We came out in the second half and played a little bit better football, but not good enough to get the win.''

Zwinak, who rushed for 128 yards on 21 carries, helped spearhead the Penn State comeback bid. He scored two of his three touchdowns in the second half. His only blemish came when he was stripped of the ball and UCF recovered late in the fourth quarter.

''I just saw it from behind. It just looked like they stripped it out. (Zach) feels bad about that, I feel bad about that,'' Penn State coach Bill O'Brien said. ''He did, he ran the ball hard tonight. I love that kid. We're with him and he's with us. It's just a tough way to end it for him. He'll be fine.''

Another offensive player who is more than fine is Hackenberg, the true freshman signal caller. He completed 75 percent of his passes for 262 yards and a touchdown in the face of frequent UCF blitzes.

''I think (Christian) is learning with every snap. I think it is a very difficult position when you are 18 years old, but he is definitely up to the challenge and I love coaching him,'' O'Brien said.

''He is a great kid and just a fantastic guy to have in our program and he will keep getting better and better every day. He's got that type of demeanor and I just think the world of that kid.''